1. Field of the Invention
This invention relates generally to a device for producing precise incremental joint movement in a patient, and more specifically to a device for producing precise temporalmandibular joint movement in a patient, wherein the device is operated by the patient during the making of internal images of the joint by magnetic resonance imaging.
2. Description of Related Art
It is known to diagnose various disorders, such as joint pain, by viewing internal images of the area under investigation at stepped positions. Such investigations can be performed by standard x-rays, by the new CT scan or by the even newer technique of magnetic resonance imaging (MRI).
For example, patients may suffer from a temporalmandibular joint (TMJ) disorder in which opening or closing of the lower jaw can be accomplished, if at all, only with severe pain or discomfort. Treating of these patients involves personal observation by a physician, which can be significantly advanced with the aid of a series of internal images made of the jaw area at spaced stages of jaw opening through MRI techniques.
In the past, the progressive opening of the temporalmandibular joint for the above diagnosis has been accomplished by the physician or a technician inserting a wedge-type dental block between the patient's jaw bones (i.e., teeth) and forcing the block rearward in "slow" incremental steps. A scissors-like forceps, having a releasable pawl mechanism for locking the forceps in each stage of jaw opening, also has been used.
The foregoing procedures have a number of disadvantages. For example, the use of the manually inserted wedge-type dental block is relatively inaccurate and requires the presence of the physician or technician with the patient for the insertion procedure. The scissors-like forceps, while more accurate, is cumbersome and unwieldy, and still requires great care for evenly-spaced steps.
Accordingly, a need exists for a device by which temporalmandibular joint incrementing in a magnetic resonance imaging procedure can be made precisely and simply without a physician or technician being in the immediate presence of the patient, and the primary purpose of this invention is to provide such a device.